Senior/Principal Java Engineer - Greater London - Juxt Ltd.

    Juxt Ltd.
    Juxt Ltd. Greater London

    2 days ago

    Description

    Job Description


    We're looking for Senior and Principal Java Developers with a strong background in low-latency systems to join us on a high-performance trading and real-time data project, for a major financial institution.

    You'll work on mission-critical applications where performance, scalability, and reliability truly matter — the kind of systems that power global trading platforms and require a deep understanding of how the JVM and Linux really work. This is an opportunity to bring world-class engineering principles to projects at the very heart of modern finance.

    Your work will focus on writing and tuning high-performance Java frameworks, improving throughput and latency, and applying event-driven, microservice-based architectures. You'll collaborate closely with other talented engineers, helping to shape elegant solutions to complex, performance-sensitive problems.

    You'll be joining an environment where good software engineering truly matters — where clean design, measurable performance, and deep system understanding are valued. This is an opportunity to work alongside recognised low-latency specialists, elevate your expertise, and contribute to systems that demand precision and technical excellence.

    We're looking for developers who are technically exceptional, but also pragmatic — engineers who love to understand how things work under the hood, measure performance precisely, and continuously refine their craft.

    Core skills

    • Strong Java skills with deep knowledge of the JVM
    • Proven experience building or optimising low-latency systems
    • Familiarity with performance tuning and profiling tools (e.g. JMH, async-profiler, Flight Recorder)
    • Solid understanding of multithreading, concurrency, and memory management
    • Experience with microservice architectures and event-driven systems
    • Strong Linux fundamentals and comfort with performance diagnostics
    • Clear communication skills and ability to articulate design and performance decisions

    Nice to have

    • Experience with high-performance messaging (Chronicle Queue/Wire, Aeron, ZeroMQ, Kafka tuning)
    • Familiarity with off-heap or direct memory structures (Chronicle Map, VarHandles, DirectByteBuffers)
    • Networking/I/O frameworks such as Netty or custom FIX engines
    • Exposure to OpenHFT, LMAX Disruptor, or similar performance-focused frameworks
    • Prior experience in trading, financial markets, or real-time data systems
    • Ability to produce clear, lightweight documentation or UML diagrams when needed

    WFH?


    These roles are hybrid - a mix of working from home and on-site collaboration in London, Canary Wharf.

    Contract type


    Both permanent and contract arrangements considered.

    Eligibility


    We can only consider candidates who have the right to work in the UK and do not require visa sponsorship. Applicants must be UK-based and within a commutable distance to London.

    Interested?


    Email with your CV and a brief introduction. Even if you're not sure you tick every box, we'd still love to hear from you - we're always keen to meet passionate, technically curious developers and can keep you in mind for future projects if this one isn't the right fit.


    #J-18808-Ljbffr
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